1. Field of the Invention
The present invention generally relates to a directional coupler for monitoring a signal exchanged in a wireless communication system and, in particular, to a directional coupler having input and output connectors integrated therein.
2. Description of the Related Art
In general, a directional coupler is designed to be used in a base station to detect a signal induced into a coupling line installed in the vicinity of a main line and extracts a signal source for examination and control purposes in a wireless communication system.
FIG. 1 is a perspective view illustrating a conventional directional coupler 100, and FIG. 2 is a sectional view illustrating the directional coupler 100 taken along line A-A′ illustrated in FIG. 1.
As shown in FIGS. 1 and 2, the directional coupler 100 comprises a rectangular housing 110, an input connector 120 connected to one end of the housing 110, an output connector 130 connected to the other end of the housing 110, a main line 151 connecting the input connector 120 to the output connector 130 for delivering a signal, a coupling line 153 installed in parallel with the main line 151, and coupling terminals 141 and 143 at both ends of the coupling line 153. One of the coupling terminals 141 and 143 is grounded through a terminating resistor (not shown).
The components of the directional coupler 100 are fixed to the housing 110 to firmly tighten the connections between the coupling line 153, the coupling terminals 141 and 143, and the terminating resistor. Each of the input and output connectors 120 and 130 is provided with a flange 121 or 131 by which it is engaged with the housing 110. The main line 15 and the coupling line 153 are spaced from each other by a distance determined according to a system-required coupling value.
In operation, the input connector 120 transfers the signal received therein to the output connector 130 via the main line 150, while a part of the signal is induced to the coupling line 153.
The above conventional directional coupler is assembled by combining a separate housing, input connector, and output connector. Therefore, the manufacturing process is complicated, lengthy, and costly. Moreover, although the input and output connectors are coaxial, the housing is not. As such, a discontinuation occurs in the process of transmitting a signal from the circular coaxial input connector to the circular coaxial output connector through the rectangular housing, thus yielding a poor impedance matching and deteriorated directivity.